Camera modules normally each include a sensor. In order to shield a sensor intended to capture visible images from the effects of light which is not to be captured by the sensor, e.g., infrared light in the case of a sensor to be used to capture visual images, a sensor is often covered by a filter. Positioning of a filter over a sensor can present various mounting issues.
While an approach to mounting an IR filter over an image sensor is shown in FIG. 1. FIG. 1 shows a filter sensor assembly 1000 which includes an IR filter 1002 which is placed above and glued to supports 1004, 1006. The supports 1004, 1004′ are secured to mounting board 1008 on which the sensor 1003 is mounted. Wires 1006, 1006′ connect the sensor to electrical contacts, e.g., on the mounting board 1008.
While the IR filter mounting arrangement shown in FIG. 1 is simple to construct, it has several disadvantages. The IR filter 1002, because it sits on top of the support walls 1004, 1004′, is subject to the risk of being scratched or crushed during shipment since it is the top most element of the assembly 1000. Furthermore light passing through the filter may bounce off one of the wires 1006 and 1006′ and be reflected onto the active area of the sensor 1008 since the sidewalls are vertical and the area over the wires 1006 is exposed to light which can be reflected onto the sensor 1003. In additional light may pass through the side of the IR filter and be reflected or otherwise reach the sensor since the sidewalls of the IR filter 1002 are exposed.
In addition to the above problems the assembly may suffer from issues relating to the use of glue between the bottom of the IR filter and the top of the supports 1004, 1004′ to secure the IR filter to the supports. Glue placed on top of the supports 1004, 1004′ may tend to ooze out when the filter 1002 is placed over the supports potentially seeping onto the sensor and/or inner surface of the IF filter and potentially interfering with light passing through the filter onto the sensor. In addition, a fair amount of glue may be needed to prevent the IR filter being shifted sideways during shipment since the sides of the IR filter may be subject to sideways forces since they are exposed on top of the supports 1004, 1004′.
In view of the above, it should be appreciated that there is a need for improved methods and apparatus for mounting a filter over an image sensor and/or for implementing a system including a filter and sensor. While it is not necessary that all embodiments address all of the problems noted above with the filter mounting arrangement shown in FIG. 1, it would be desirable if a filter mounting arrangement and/or filter and sensor assembly could be developed which would address one or more of the above discussed problems.